Acute neurobehavioral effects of toluene vapor will be measured by standardized test battery, and expressed in "ethanol equivalent units", at the ACGIH recommended action level and TLV. Each subject is exposed for 7 hours to 0, 50, or 100 ppm over 3 consecutive days. A behavioral evaluation of visuomotor skills, visual perception, interference, dexterity, and short-term memory will be conducted on a micro-computer given at 8 AM, 12 Noon, and 4 PM. The behavioral test battery will also determine the effects of ingested ethanol at 0, 0.30, and 0.60 g/kg body weight. The rationale for including the ethanol component is: 1) it serves as a positive control for the toluene experiment, and 2) it permits a comparison of behavioral effects between solvents. Chronic effects of solvent exposure have been equated to premature aging. Similarly, it would be useful to express an acute solvent effect by an index of "ethanol equivalent units" since acute neurobehavioral ethanol toxicity is well described. The proposed study will be completed in 3 experiments; a pilot study will determine the required number of subjects, and the second and third experiment will examine toluence and ethanol, respectively. Subjects are randomly assigned to 1 of 3 orders of exposure presentation (0, 50, 100 ppm). To minimize a possible bias in response to differences in exposure, the odor will be masked by an aromatic agent. Depending on the results of the pilot study an estimated 40 subjects will be in experiments 2 and 3. Paid volunteers with at least 1 year of college, aged 18-35 years old, with no history of solvent exposure, and who consume less than 30 g ethanol per day will be chosen. Inter-subject variation in solvent absorbance will be monitored in expiratory air at each test point, and total toluene uptake will be determined from a 24-hour urinary methylhippuric acid sample. The contribution of the proposed study is to examine effects of low concentrations of toluene on human abilities which could result in sub-clinical CNS disorders affecting work performance or health. Successful completion of these studies should represent an improvement in research methodology by: 1) using a standardized test battery, 2) by introducing an index of solvent potency in ethanol equivalent units, and 3) determining if an acute solvent effect exists at relevant industrial exposures which will aid in interpretation of epidemiological investigations of chronic solvent effects. Most of the test battery has been recommended for use in future epidemiological studies by NIOSH and WHO, thus the results will be useful in the design and interpretation of future studies.